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1.
研究了在磷酸钙催化剂上二异丁基乙缩醛裂解制乙烯基异丁醚反应的活性和选择性,其中较好的催化剂是在500度焙烧的Ca3(PO4)2(1)。考察了工艺条件对反应结果的影响,表明在反应温度约300度,缩醛的LHSV=1.0h^-1时得到最佳反应结果:转化率约98.6%,选择性接近100%,用TPD法测定了催化剂表面的酸度和碱度,并与活性和选择性进行了关联。  相似文献   

2.
在强酸性阳离子交换树脂催化剂存在下,以异丁醛、1,2-丙二醇为原料,直接合成异丁醛1,2-丙二醇缩醛.分别研究了反应温度、反应时间、原料配比、带水剂、催化剂用量等条件对合成反应的影响,确定了最佳工艺条件:反应温度90-95℃,反应时间2.5h,n(异丁醛):n(1,2-丙二醇)=1:1.2,催化剂用量1.5g,带水剂环己烷40mL(异丁醛为0.1mol的情况下).异丁醛1,2-丙二醇缩醛的收率达到91.16%,产品纯度w(异丁醛1,2-丙二醇缩醛)达到98.5%以上.催化剂不经处理可多次循环使用.该催化剂具有价廉易得、催化活性好、不腐蚀设备、无环境污染等优点.  相似文献   

3.
研究了以四氯化锡为催化剂,苯甲酸和异丁醇直接合成苯甲酸异丁酯的优化反应条件:以0.1mol苯甲酸为基准,n(异丁醇)/n(苯甲酸)=4,催化剂用量为苯甲酸质量的9.5%,反应在回流温度下进行5h,苯甲酸的酯化率可达98.05%,质量分数在99%以上。该催化剂易分离回收,可重复使用。  相似文献   

4.
利用相转移催化剂催化合成乙酸异丁酯.最佳反应条件如下:催化剂用量0.5g/0.1mol异丁醇、酸醇比1.2:1.反应时间100分钟.收率77.36%。实验证明,相转移催化对该酯化反应是高效、低成本和实用的合成方法。  相似文献   

5.
SO42-/TiO2-MoO3催化合成苯甲醛乙二醇缩醛   总被引:1,自引:0,他引:1  
以固体超强酸SO4^2-/TiO2-MoO3为多相催化剂,对以苯甲醛和乙二醇为原料合成苯甲醛乙二醇缩醛的反应条件进行了研究。实验表明:SO4^2-/TiO2-MoO3是合成苯甲醛乙二醇缩醛的良好催化剂,较系统地研究了醛醇摩尔比、催化剂用量、反应时间诸因素对收率的影响。最佳反应条件为:n(苯甲醛):n(乙二醇)=1:1.3,催化剂用量为反应物料总质量的0.75%,环己烷为带水剂,反应时间40min。上述条件下,苯甲醛乙二醇缩醛的收率可达82.7%.  相似文献   

6.
TiSiW12O40/TiO2催化合成丁醛乙二醇缩醛   总被引:1,自引:0,他引:1  
以固载杂多酸盐TiSiW12O40/TiO2为多相催化剂,对以丁醛和乙二醇为原料合成丁醛乙二醇缩醛的反应条件进行了研究,实验表明TiSiW12O40/TiO2是合成丁醛乙二醇缩醛的良好催化剂,较系统地研究了醛醇的物质的量的比、催化剂用量、反应时间诸因素对收率的影响,得到最佳反应条件为:n(丁醛):n(乙二醇)=1:1.5,催化剂用量为反应物料总质量的0.5%,环己烷为带水剂,反应时间1.0h,上述条件下,丁醛乙二醇缩醛的收率可达81.9%。  相似文献   

7.
在Pt/Al2O3催化剂上,用外循环无梯度反应器研究了异丁醇内扩散对异丁醇完全氧化动力学的影响。用0.45~0.60mm催化剂,反应在动力学区域进行,异丁醇完全氧化的动力学用-0.6级速度方程描述。当催化剂颗粒增大到4mm时,反应受内扩散控制,在内扩散区域异丁醇反应级数变为-0.01级。测定了催化剂有效因子η,其值在0.21~0.61之间。它表明孔扩散阻力严重。在温度恒定时,ηexp值随异丁醇分压的升高而增加。在异丁醇分压固定时,ηexp值随反应温度升高而下降。反应在动力学区域时,异丁醇完全氧化的活化能为26.0kJ/mol,而在内扩散区域时,反应活化能为23.7kJ/mol。  相似文献   

8.
活性炭负载磷钨酸催化合成香料乙酸异丁酯   总被引:2,自引:0,他引:2  
利用负载磷钨酸为催化剂合成乙酸异丁酯,以异丁醇和冰乙酸为合成原料,反应条件温和,反应速度快,产率高。探讨并找出最佳条件,在醇酸摩尔比为1:1.6,催化剂用量占反应物总量的7.23%。反应时间为100min时,得到的乙酸异丁酯产率最高,为91.28%。  相似文献   

9.
硫酸氢钠催化合成正丁醛1,2-丙二醇缩醛   总被引:2,自引:0,他引:2  
以NaHSO4为催化剂,对以正丁醛(Ⅱ)和1,2-丙二醇(Ⅲ)为原料合成正丁醛1,2-丙二醇缩醛(Ⅰ)的反应条件进行了研究,较系统地探讨了醛醇摩尔配比、催化剂用量、反应时间诸因素对收率的影响,实验表明:NaHSO4是合成正丁醛1,2-丙二醇缩醛的良好催化剂.最佳反应条件为:n(醛):n(醇)=1:3,催化剂用量为反应物总质量的2.5%,带水剂环已烷为15mL,反应时间1.25h.上述条件下,正丁醛1,2-丙二醇缩醛的收率可达71.6%。  相似文献   

10.
用大孔阳离子交换树脂和磷钨酸制得离子交换树脂固载磷钨酸催化剂,用此催化剂合成了苯甲醛正己硫醇缩醛,考察了影响其收率的因素.发现催化合成的优化条件为:苯甲醛:正己硫醇:催化剂:二氯甲烷=0.1mol:0.215mol:2.0g:35.0mL,43℃回流下进行,反应时间5.0h,收率可达86.3%,由此可见,离子交换树脂固载磷钨酸为催化剂对苯甲醛和正己硫醇缩醛反应具有较高的催化活性,且稳定性较佳,可重复使用.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

18.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

19.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

20.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

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